Download Southern Ocean Heat and Carbon Uptake

Southern Ocean Heat and Carbon Uptake
An Update on the Progress by the:
JOINT U.S. CLIVAR/OCB WORKING GROUP
Co-Chairs:
Igor Kamenkovich (U. Miami)
Joellen Russell (U. Arizona)
Russell – July 25, 2013
JOINT U.S. CLIVAR/OCB WORKING GROUP:
Heat and Carbon Uptake by the Southern Ocean
Goals:
•
Improve understanding of
the role of mesoscale
eddies in the heat and
carbon uptake by the
Southern Ocean.
•
Improve understanding of
how the Southern Ocean
stratification, circulation
and heat and carbon
uptake will respond to a
changing climate.
Russell – July 25, 2013
What is the role of the Southern Ocean in
the global climate system?
1. It may account for up to half of the annual oceanic
uptake of anthropogenic carbon dioxide from the
atmosphere (cf., Gruber et al., 2009)
2. Vertical exchange in the Southern Ocean is
responsible for supplying nutrients that fertilize threequarters of the biological production in the global
ocean north of 30°S (Sarmiento et al., 2004)
3. It may account for up to 70 ± 30% of the excess heat
that is transferred from the atmosphere into the ocean
each year (see analysis of IPCC AR4 models)
4. Southern Ocean winds and buoyancy fluxes are the
principal source of energy for driving the large scale
deep meridional overturning circulation throughout the
ocean (e.g., Toggweiler and Samuels, 1998; Marshall
and Speer, 2012)
Russell – July 25, 2013
The Antarctic Circumpolar Current
System
Courtesy:
Lynne Talley
Russell – July 25, 2013
SOWG Outcomes and Deliverables
• Observationally-based data/model metrics for the consistent evaluation of
modeling efforts by Southern Ocean and Antarctic scientists.
• A White Paper that:
(i) assesses the state of our understanding of the role of eddies in the
Southern Ocean in both the data and the models;
(ii) identifies the most critical observational targets needed to fill in gaps
in our understanding of the role of the Southern Ocean in present and
future climate.
• A Workshop/Conference jointly sponsored with the Oceanic Carbon
Uptake Working Group, with the goal of:
(i) sharing the developed metrics for model evaluations;
(ii) identifying important biases in the AR5/CMIP5-type model simulations
of present and future climate, stemming from the lack of mesoscale
eddies;
(iii) providing guidance for estimating and reducing uncertainty in climate
projections.
Russell – July 25, 2013
• A summary of WG activities/products for the U S CLIVAR and OCB
SOWG Planned Activities
• Spring/Summer 2012 – Bi-monthly teleconferences: progress on development of
targets and model assessment
• Fall 2012 – 1st WG Meeting to: a) discuss/propose potential targeted process or
measurement campaigns that will allow alignment of model-derived and
observational evidence; and b) discuss/propose targeted process or sensitivity
studies in available models with appropriate tracers and outputs to match our
observational colleagues efforts
• Spring 2012/2013 – Bi-monthly teleconferences: progress on development of
measurement campaigns and modeling studies
• Summer 2013 – Bi-monthly teleconferences: plan and arrange a larger
workshop/conference to frame science questions motivated by new
measurements, to evaluate the ability of high-resolution models to reproduce
these effects, and to foster climate model improvements.
• 2012-2013 – conference calls every 6 months involving co-chairs of this WG (I.
Kamenkovich and J. Russell) and the WG on “Oceanic carbon uptake in the
CMIP-5 models” (“Carbon Uptake WG”, cochairs: A. Bracco, C. Deutsch and T.
Ito), to collaborate on the interpretation of model analysis in the Southern Ocean
• Fall/Winter 2013 – Monthly teleconferences: write/submit white paper,
summarizing key results from WG and workshop/conference.
• Spring/Summer 2014 – 2nd WG Meeting and workshop/conference, joint with the
Carbon Uptake WG, to update wider community on progress
Russell – July 25, 2013
Responsiveness to agency concerns:
This Working Group addresses key concerns of three supporting
agencies, in particular:
NOAA: Describing and understanding the state of the climate system
through integrated observations and analysis. Improving climate
predictive capability from weeks to decades.
NASA: Understanding how climate variations induce changes in the
global ocean circulation; improving predictions of climate variability and
change [using satellite observations]; understanding the role of slowly
varying components of the earth system (e.g. ocean and ice) in climate.
NSF: Advancing discovery, knowledge and understanding in climate
science; understanding processes and exploiting new observing
techniques; analyzing process studies to address known deficiencies in
climate models; identifying critically important questions and the facilities
and research required to address them; providing feedback on longrange scientific priorities.
Russell – July 25, 2013
New Tools:
1) Southern Ocean Observations
2) Southern Ocean State Estimate
3) Mesoscale-Resolving Models
Russell – July 25, 2013
SOOS Observing System
Components
The locations of more than 60,000 Argo profiles
of temperature and salinity collected during the
24 months of the IPY. Courtesy of Mathieu
Balbeoch, JCOMMOPS
White circles indicate location of current or
planned drill holes through ice shelves, allowing
sampling of underlying ocean waters. .
Map of proposed moored arrays (red
circles) to sample the primary Antarctic
Bottom Water formation and export sites
Repeat hydrographic sections to be
occupied by SOOS. Symbols indicate
the WOCE/CLIVAR designations for
each line
The ship-of-opportunity lines in
the Southern Ocean that
contribute to SOOS.
Hydrographic sections (lines) and
moorings (circles) occupied as
contributions to the IPY SASSI
program.
Russell – July 25, 2013
The Southern Ocean State Estimate
(SOSE)
(Nominal Resolution is 1/6°)
M. Mazloff, P. Heimbach, and C.
Wunsch, 2010: “An Eddy-Permitting
Southern Ocean State Estimate.”
J. Phys. Oceanogr., 40, 880–899.
doi: 10.1175/2009JPO4236.1
Southern Ocean State Estimation
http://sose.ucsd.edu/
A modern general circulation model, the
MITgcm, is least squares fit to all
available ocean observations. This is
accomplished iteratively through the
adjoint method. The result is a physically
realistic estimate of the ocean state.
SOSE is being produced by Matthew
Mazloff as part of the ECCO consortium
and funded by the National Science
Foundation. Computational resources are
provided in part by the NSF TeraGrid.
Russell – July 25, 2013
Eddy Kinetic
Energy in the
Southern Ocean
(Delworth et al., 2012)
Russell – July 25, 2013
SOSE
CM2p5
SST
CM2p5 - SOSE
Russell – July 25, 2013
New Metrics
Russell – July 25, 2013
Person
Affiliation
Area of Interest
Metric(s)
Cecilia Bitz
U. Washington
Role of Sea Ice in Climate
Sea Ice Extent/Volume/Seasonality
Raffaele Ferrari
MIT
Ocean Turbulence
Eddy Kinetic Energy; Eddy-induced diffusivities and
heat transport/uptake
Sarah Gille
UCSD/SIO
Air/Sea Exchange
Mixed-layer depth; Heat Content (400m)
Non-solubility pCO2 variance
Robert Hallberg
NOAA/GFDL
Ocean Dynamics
Water mass properties (upper 2000m and abyssal);
Age tracer distribution; Drake Passage transport
Ken Johnson
MBARI
Chemical Sensors/
Biogeochemical Cycles
Seasonal cycle of nitrate
Igor Kamenkovich
U. Miami
Mesoscale Eddies/ Role of
SO in global MOC
Stratification at the northern flank of the SO; Eddyinduced diffusivities
Irina Marinov
U. Pennsylvania
Carbon Cycle/Ecology
Oxygen, Temperature, Salinity
Precipitation; Background nutrients
Matt Mazloff
UCSD/SIO
State Estimates
Mean dynamic topography;
Temperature transport through the Drake Passage
Joellen Russell
U. Arizona
Role of Ocean in Climate
Strength and position of SO Westerly Winds
Area of deep-water outcrop; Depth of AAIW isopycnal
Jorge Sarmiento
Princeton U.
Biogeochemical Cycles
Fractional uptake of heat and carbon by the SO
Kevin Speer
Florida State U.
Large-Scale Circulation
Stratification north and south of ACC (esp. SAMW)
Mean flow/shear in SE Pacific; tracer spreading rates
Lynne Talley
UCSD/SIO
Physical Oceanography
Repeat hydrography inventories
Rik Wanninkhof
NOAA/AOML
Inorganic Carbon Cycle
Aragonite saturation state
Russell – July 25, 2013
Bathymetry – Depth of the Sea Floor (m)
ETOPO2
GFDL-ESM2M
BCC-CSM2
CSIRO-Mk3.6
GFDL-CM2.5
CanESM2
HadGEM2-ES
MRI
CSIRO is much too smooth
Russell – July 25, 2013
Annual mean, 2001-2005
Sea Surface Height
Values are net transport
through Drake Passage
Sea Surface Height (m)
GODAS (2006-10)
GFDL-ESM2M
133.7 Sv
BCC-CSM2
156.6 Sv
CSIRO-Mk3.6
108.2 Sv
GFDL-CM2.5
114.2 Sv
CanESM2
154.6 Sv
HadGEM2-ES
172.1 Sv
MRI
115.5 Sv
Russell – July 25, 2013
Simulated Sea Surface Height (cm) Annual mean, 2001-2005
GFDL
Observed
TOPEX
CM2p6
CM2p5
ESM2M
CM2p1
ACCESS1.0
CanESM2
CCSM4
CESM1-BGC
CNRM-CM5
CSIRO-Mk3.6
FGOALS-S2
FIO-ESM
IPSL-CM5-LR
MIROC5
MRI-CGCM3
NorESM1-M
This is a different subset of CMIP5 models
Russell – July 25, 2013
Simulated Zonal Wind Stress (N/m2)Annual mean, 2001-2005
CCSM4
IPSL
Too strong easterlies
Russell – July 25, 2013
Drake Passage Transport:
Zonal Velocity at 69°W
Annual mean, 2001-2005
Zonal Velocity
Values are net transport
through Drake Passage
SOSE (2008)
148.1 Sv
GFDL-ESM2M
133.7 Sv
BCC-CSM2
156.6 Sv
CSIRO-Mk3.6
108.2 Sv
GFDL-CM2.5
114.2 Sv
CanESM2
154.6 Sv
HadGEM2-ES
172.1 Sv
MRI
115.5 Sv
Frontal structure is not captured by lower resolution models
Russell – July 25, 2013
Simulated Winds vs ACC Transport
CCSM4
SOSE 
 CM2.1
 ESM2M
CM2.5 
CM2.6 
CNRM
Maximum Zonal Mean Zonal Wind Stress (N/m2)
Maximum Zonal Wind Stress
ACC Transport (Sv)
ACC Transport (Sv)
CCSM4
MIROC5
Annual mean, 2001-2005
Zonal Mean Wind Stress
between 80°S-30°S
SOSE 
CM2.1 
ESM2M 
 CM2.5
IPSL
CM2.6 
CNRM
Latitude of Maximum Zonal Mean Zonal Wind
Stress
Latitude of Maximum Stress
Russell – July 25, 2013
Change in Mean Wind Speed (m/s)
RCP8.5 (2080-2100) – Historical (1980-2000)
Russell – July 25, 2013
Surface Water pH Difference
Annual mean (20012005)
(From GLODAP/WOA2001)
GFDL-ESM2M
MIROC-ESM
CanESM2
MRI-ESM1
Observed pH was
calculated from the
GLODAP TCO2 and
Alkalinity and the
World Ocean Atlas
(2001) Temperature
and Salinity using
the formulas from
Dickson (2007)
Russell – July 25, 2013
Southern Ocean pH at 60°S
Observed
MRI-ESM1
Annual mean (20012005)
GFDL-ESM2M
CanESM2
Observed pH was calculated from the GLODAP TCO2 and Alkalinity and the
World Ocean Atlas (2001) Temperature and Salinity using the formulas from
Russell – July 25, 2013
Colum Inventory DIC Difference
Annual mean (20012005)
(mol/m2; Difference From GLODAP)
GFDL-ESM2M
MIROC-ESM
CanESM2
MRI-ESM1
Some of the column
inventory difference
may reflect differences
in the model
bathymetry from
observed
Russell – July 25, 2013